Vehicle door and a method to make such a door

ABSTRACT

A vehicle door has a supportive frame ( 10 ). A waist rail ( 14 ) and a side impact guard beam ( 22 ) are formed integrally with the supportive frame. The entire frame is made of high strength sheet steel. The door is produced by hot stamping a steel sheet blank into the shape of a supportive door frame that includes an integral waist rail ( 14 ) and a side impact guard beam ( 22 ), and hardening the shaped door frame while the frame remains in the shaping tools, and fastening an outer panel ( 31 ) to the finished door such that the side collision guard beam ( 22 ) of the frame will lie close to the outer panel ( 31 ).

This application is a continuation-in-part of International ApplicationPCT/SE02/00219, having an international filing date of Feb. 8, 2002,published in English under PCT Article 21(2).

FIELD OF INVENTION

The present invention relates to a vehicle door which comprises asupportive door frame that includes a waist rail and a side impactguard, and which further comprises an outer panel and inner trimmaterial fastened to the frame, wherein the side impact guard ispositioned close to the outer panel. The invention also relates to amethod of manufacturing a vehicle door.

TECHNICAL BACKGROUND OF THE INVENTION AND A BRIEF DESCRIPTION OF KNOWNTECHNOLOGY

Modern vehicle doors normally comprise a supportive deep-drawn so-calledinner panel which has the thickness of the entire door. An outer panelis folded around the edges of the inner panel and fastened with glue.The inner panel is deep-drawn and cannot therefore be produced fromhigh-strength steel. A so-called waist rail beneath the window is weldedto the inner panel and can be placed either inwardly of or outwardly ofthe window. A side impact guard beam made of steel that has aconsiderably higher mechanical strength than the steel from which theinner panel is made is also welded to the inner panel and placed nearestthe outer panel. A relatively flat trim is fastened to the inner panel.The inner door components, such as locks, window guides and windowelevators, arc mounted within the deep inner panel, i.e. on the outsideof said panel.

THE OBJECT OF THE INVENTION AND A SUMMARY OF THE INVENTION

An object of the present invention is to provide a lightweight, strongvehicle door which can be produced cheaply and with which doorcomponents, such as locks, window guides and window elevators, can bereadily fitted and easily accessed. In principle, this object isachieved with a vehicle door in which the waist rail and the side impactguard are both produced integrally with the supporting door frame. Thedoor frame is suitably manufactured by hot stamping a sheet steel blankto form a supportive door frame that has a waist rail and a side impactguard beam integral therewith, and then hardening the shaped door framewith the frame remaining in the mould tools. The forming is facilitatedby the fact that the door frame can be made thin in relation to the fullthickness of the door, therewith enabling a door frame of high strengthsteel to be produced. In the case of a typically constructed door thathas a deeper configuration, it is necessary to use steel that has alower strength.

Manufacture of the door is completed by attaching an outer panel to thesupportive door frame, such that the side impact guard beam included inthe frame will be situated close to the outer panel.

A door frame that has a very high mechanical strength can be produced inthis way, and the major part of the thickness of the door may besituated on the inside of the door frame instead of on the outside ofthe supportive part. This facilitates shaping and enables doorcomponents relating to locks and window elevators to be fitted to theframe while still being easily accessed between the frame and thereadily removed trim. The invention is defined in the accompanyingClaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The computer drawn figures illustrate the supportive parts of a vehicledoor by way of an example of the invention.

FIG. 1 is a perspective view of the supportive frame of the vehicledoor, as seen from the vehicle interior.

FIG. 2 is a side view of the frame as seen externally.

FIGS. 3 and 4 are views seen in the direction of respective arrows 3 and4 in FIG. 2.

FIG. 5 is a sectioned view taken on the line 5—5 in FIG. 1.

FIG. 6 is a sectioned view of an alternative embodiment of the doorframe.

FIG. 7 is a perspective view of a further alternative embodiment of asupportive door frame, as seen from the vehicle interior.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Shown in FIG. 1 is a frame 10 belonging to the left-hand door of avehicle, said frame being seen from inside the vehicle interior. FIG. 2is an external view of the same frame. The frame is hot stamped from aflat steel sheet to obtain a ring-shaped hat-beam 13–16 that includes acrown 12 and side flanges 17, 18 of varying widths. The cross-section ofthe hat beam is shown in FIG. 5. The crown or hump of the beam faces intowards the vehicle interior. The hat beam includes four straight parts13, 14, 15, 16 which are joined together with the aid of bends. A hole20, 21 is formed in the centre of the ring-shaped hat beam, and a sideimpact guard beam 22 extends between the beam parts 13 and 15 andbridges the hole 20, 21. The beam 22 may also have a hat profile withthe crown of the hat facing inwards as shown, and may also include aspot-welded cover 23. Alternatively, it may have a differentcross-sectional shape, for instance the shape of a double-hat profileand may be positioned with its open side facing inwardly towards thevehicle interior as shown in FIG. 6. The hat beam 11 may also haveanother cross-section profile and may have different profiles atdifferent locations and, for instance, have the form of a double hat atgiven locations. The door frame 10 is provided on its side that facestowards the vehicle interior with an attachment bracket 25, which may besecured with spot welds. The attachment bracket 25 may also convenientlyhave a hat profile, therewith adding to the strength of the door frame.

A box 27 accommodating the door lock is spot welded to the door frame.FIG. 3 shows hinge fastening holes 28, 29. As will be seen from FIG. 2,a window arch 30 is attached to the door frame 10, wherein window guides(not shown) can extend down in the interspace between the guard beam 22and the attachment bracket 23.

FIG. 5 shows the outer door panel 31 and interior trim 32. The trim iscomprised of hard plastic foam that includes an outer layer of plastic,fabric, leather or some other suitable material. It is attached to thehat beam 13, 15, 16 of the door frame and to the attachment bracket 25.Its upper edge is sealed off with a strip against the window pane. Theouter panel 31 is folded around the outer side flange 17 of the hatbeam, as shown, and secured with glue and scaled with a rubber stripagainst the window pane. The outer panel 31 lies close to the frame 10and the side impact guard beam 22 of said frame, and all interior doorcomponents are positioned between the frame 10 and the interior trim andfastened to the frame or to said attachment bracket 25, therewithenabling said components to be easily reached after having removed theinterior trim. As illustrated in the drawing, the side impact guard beam22 is directly adjacent to the outer panel 31, and no intermediatestructural components are disposed therebetween. The upper beam 14 ofthe frame 10 forms a so-called waist rail, i.e. a beam fitted beneaththe window, this beam now being integrated in the frame instead of beingwelded separately thereto as in the case of conventional vehicle doors.Many conventional vehicle doors also include a separate lowerreinforcement beam, this lower beam being replaced by the lower framebeam 16 in the illustrated case.

FIG. 6 is a sectioned view of an alternative embodiment of the frame 10,where the upper beam 14, the waist rail, has been extended in on theinside of the window, in the bends towards the beams 13, 15. TheA-pillar and B-pillar of the vehicle are often placed inwardly inrelation to the outside of the door, wherein the inwardly positionedwaist rail shown in FIG. 6 can be positioned to overlap said pillars atleast to some extent, so that the beam, or rail, will be clamped axiallybetween the A-pillar and B-pillar in the event of a frontal collision,and therewith transfer force from the A-pillar to the B-pillar. An outerpanel 31, interior trim 32, window 33 and window guides 34 are alsoshown in the figure. The illustrated side collision guard beam 22 has adouble-hat profile which is open towards the vehicle interior.

Method of Manufacture

The door frame 10 is produced from a flat metal blank which is heated toits austenitic temperature and passed, whilst hot, into a hot stampingpress and shaped in one stroke of the press to the shape desired in thespace of one second. The shaped blank is then left between the tools ordies and there cooled until hardened. Because the shaped blank, i.e. thedoor frame 10, is allowed to harden in the fixture in this way, it isunable to warp or buckle during the hardening process.

When using a boron steel, i.e. a simple carbon-manganese steel alloyedwith boron, there can be achieved a yield strength of 1100 N/mm² and atensile strength of 1500 N/mm² or greater, wherewith the entire doorframe, including the reinforcement beam, will have the same strength.One significant advantage afforded by this method of manufacture is thata steel having a strain capacity in excess of 7% before rupture can beobtained. The depth of the illustrated door frame is not greater thanthe height of the crown on the hat beam, and the material thickness may,for instance, be 1.0–1.5 mm, with the entire frame having the samematerial thickness. There can also be used a so-called tailor blank,i.e. a blank which is laser-welded together from steel sheets ofdifferent thicknesses or analyses. The attachment holes 28, 29 in theframe 10 can be made in the blank prior to shaping the same, i.e. priorto hardening. Alternatively, the holes can be cut with the aid of lasersor punched in the finished, hardened frame. However, because the hingesand other components may be welded in place in accordance with analternative method, the holes may be omitted when this alternative isused.

Because the door frame 10 may be made thin, shaping of the blank can beeffected more readily, therewith enabling the door frame to be producedby cold-shaping high strength steel sheet as an alternative. However, itis not possible to use in this alternative method steel sheet that hasthe same high yield strength as that reached in the aforedescribed hotstamping method, with which yield strengths of at least 1000 N/mm² areattained. However, there can be used high strength steel sheet that hasa yield strength of at least 350 N/mm² and an tensile strength of atleast 600 N/mm². An ultra-high strength steel having a yield point of500 N/mm² and a tensile strength of 800 N/mm² can probably be used. Therupture strain, however, will be less when cold forming than whenapplying the described hot stamp method.

FIG. 7 illustrates a further embodiment of a supportive door frame for avehicle, in accordance with the present invention. A guard beam isgenerally designated by reference numeral 35. The guard beam 35 divergesinto two separate beam sections 36, 37 in a direction from the left sideof the door frame to the right side of the door frame, as shown in FIG.7. Vertical supporting elements, designated by reference numerals 38 and39, extend in a substantially perpendicular orientation from the guardbeam 35, proximate to the location at which the guard beam diverges intothe two separate beam sections 36 and 37. Vertical support element 38extends from the guard beam 35 to the lower side flange 18 of thevehicle door, while vertical supporting element 39 extends from theguard beam 35 to the upper side flange 17 of the vehicle door. The guardbeam 35, the guard beam sections 36 and 37, and the vertical supportingelements 38 and 39, define therebetween openings 40, 41, 42, 43 and 44,as illustrated by FIG. 7. The embodiment illustrated by FIG. 7 providesenhanced support because the guard element is not limited to a singleguard beam, but includes both vertical supporting elements 38 and 39,and guard beam sections 36 and 37.

Although FIG. 7 illustrates that the guard beam 35 diverges into twoseparate beam sections 36, 37, it is also within the scope of thepresent invention to provide a unitary guard beam 35, which does notdiverge into separate guard beam sections, extending laterally betweenthe two opposed sides of the door frame. Vertical supporting elements,similar to those designated by reference numerals 38 and 39 in FIG. 7,can extend downwardly and upwardly, respectively, from the single guardbeam in a substantially perpendicular orientation relative to the singleguard beam.

Preferably, in the embodiments disclosed herein, the guard element isclose to the outer door panel but does not directly contact the outerdoor panel to avoid causing dents on the painted outer panel. Therefore,as discussed herein, the vehicle door in accordance with the presentinvention is arranged such that the side impact guard is positionedclose to the outer panel of the vehicle door. Preferably, the distanceof separation between the side impact guard and the outer door panelwill be in the range of approximately between 2 mm. through 1 cm.

1. A vehicle door comprising a steel supportive door frame (10) thatincludes a waist rail (14) and a side impact guard (22), and furthercomprising an outer panel (31) and interior trim (32) fastened to theframe, wherein the side impact guard is positioned directly adjacent theouter panel with no intermediate structural components disposedtherebetween, characterised in that the waist rail (14) and the sideimpact guard (22) are both formed integrally with the door frame (10),in that the steel of the door frame has a yield strength of at least 350N/mm², and in that the door frame (10) has the form of ring-shaped hatbeam (13, 16) having inner and outer side flanges (17, 18) of varyingwidths, the crown of the hat beam facing towards the vehicle interior,wherein the side impact guard (22) bridges a hole (20, 21) formedbetween the inner side flanges (18) of the ring-shaped hat beam, an edgeof said outer panel (31) being fastened to an edge of the outer sideflange.
 2. The vehicle door as claimed in claim 1, characterised in thatthe door frame (10) is formed from hot stamped and hardened steel sheet.3. The vehicle door according to claim 1, characterised in that saidside impact guard (22) is a beam.
 4. The vehicle door according to claim3, characterised in that said side impact guard (35) includes at leastone supporting element (38, 39) extending from one side of said beam. 5.A vehicle door comprising a steel supportive door frame (10) thatincludes a waist rail (14) and a side impact guard (22), and furthercomprising an outer panel (31) and interior trim (32) fastened to theframe, wherein the side impact guard is positioned directly adjacent theouter panel with no intermediate structural components disposedtherebetween, characterised in that the waist rail (14) and the sideimpact guard (22) are both formed integrally with the door frame (10),and in that the steel of the door frame has a yield strength of at least900 N/mm²; and in that the door frame (10) has the form of ring-shapedhat beam (13, 16) having inner and outer side flanges (17, 18) ofvarying widths, the crown of the hat beam facing towards the vehicleinterior, wherein the side impact guard (22) bridges a hole (20, 21)formed between the inner side flanges (18) of the ring-shaped hat beam,an edge of said outer panel (31) being fastened to an edge of the outerside flange.
 6. The vehicle door as claimed in claim 5, characterised inthat said steel has a strain capacity of at least 7% before rupture. 7.A vehicle door comprising a steel supportive door frame (10) thatincludes a waist rail (14) and a side impact guard (22), and furthercomprising an outer panel (31) and interior trim (32) fastened to theframe, wherein the side impact guard is positioned close to the outerpanel, characterised in that the waist rail (14) and the side impactguard (22) are both formed integrally with the door frame (10), in thatthe steel of the door frame has a yield strength of at least 350 N/mm²,and in that the door frame (10) has the form of ring-shaped hat beam(13, 16) having side flanges (17, 18) of varying widths, wherein theside impact guard (22) bridges a hole (20, 21) formed between the innerside flanges (18) of the ring-shaped hat beam; the crown (12) of the hatbeam (13, 16) facing towards the vehicle interior; and an attachmentbracket for attachment of the interior trim (32) is fastened to the hatbeam (11) and bridges the hole (20, 21) formed between the inner sideflanges (18) of the ring-shaped hat beam, wherein space for a window isformed between the attachment bracket and the side impact guard (22). 8.A vehicle door comprising a steel supportive door frame (10) thatincludes a waist rail (14) and a side impact guard (22), and furthercomprising an outer panel (31) and interior trim (32) fastened to theframe, wherein the side impact guard is positioned close to the outerpanel, characterised in that the waist rail (14) and the side impactguard (22) are both formed integrally with the door frame (10), and inthat the steel of the door frame has a yield strength of at least 350N/mm²; in that said side impact guard (22) is a beam; and in that saidside impact guard (35) includes said at least one supporting element(38, 39) extending from two opposed sides of said beam, wherein saidbeam and said supporting elements are generally configured, at least inpart, in the form of a cross.
 9. A vehicle door comprising a steelsupportive door frame (10) that includes a waist rail (14) and a sideimpact guard (22), and further comprising an outer panel (31) andinterior trim (32) fastened to the frame, wherein the side impact guardis positioned close to the outer panel, characterised in that the waistrail (14) and the side impact guard (22) are both formed integrally withthe door frame (10), and in that the steel of the door frame has a yieldstrength of at least 350 N/mm²; in that said side impact guard (22) is abeam; in that said side impact guard (35) includes at least onesupporting element (38, 39) extending from one side of said beam; and inthat said side impact guard (35) and said at least one supportingelement (38, 39) are oriented substantially perpendicular relative toeach other.
 10. A vehicle door comprising a steel supportive door frame(10) that includes a waist rail (14) and a side impact guard (22), andfurther comprising an outer panel (31) and interior trim (32) fastenedto the frame, said frame having the form of a hat beam with inner andouter side flanges, the crown of the hat beam facing towards the vehicleinterior, wherein the side impact guard is positioned directly adjacentthe outer panel with no intermediate structural components disposedtherebetween, characterised in that the waist rail (14) and the sideimpact guard (22) are both formed integrally with the door frame (10),and in that the steel of the door frame has a yield strength of at least350 N/mm²; in that said side impact guard (22) is a beam; and in thatsaid beam comprises a main body (35) which diverges into two separatebeam sections (36, 37), an edge of said outer panel (31) being fastenedto an edge of the outer side flange.
 11. The vehicle door according toclaim 10, characterised in that said side impact guard includes at leastone supporting element extending from said beam.
 12. A vehicle doorcomprising: a supportive ring-shaped steel frame carrying an outer paneland an interior trim, said steel frame comprising a waist rail, a bottomrail, two standing rails, and bends coupling the rails together, saidrails and said bends having a hat profile with a crown facing towardsthe interior of the vehicle, and inner and outer side flanges integrallyformed from a single steel sheet, an impact guard bridging a hole formedbetween the inner flanges of the rails of the frame, said impact guardbeing positioned directly adjacent said outer panel with no intermediatestructural components disposed therebetween, the outer side flange ofthe frame having varying width, and the outer panel being fastened alongan edge of the outer flange.
 13. The vehicle door according to claim 12,wherein the outer panel is folded around the edge of the outer sideflange of the frame.